In August 1957, the U.S. Navy called for replacement proposals for the piston enginedLockheed P2V Neptune (later redesignated P-2) and Martin P5M Marlin (later redesignated P-5) with a more advanced aircraft to conduct maritime patrol and anti-submarine warfare. Modifying an existing aircraft was expected to save on cost and allow rapid introduction into the fleet. Lockheed suggested a military version of their L-188 Electra, which was still in development and had yet to fly. In April 1958, Lockheed won the competition and was awarded an initial research and development contract in May.[4]

The first production version, designated P3V-1, was launched on 15 April 1961. Initial squadron deliveries to Patrol Squadron Eight (VP-8) and Patrol Squadron Forty Four (VP-44) at Naval Air Station Patuxent River, Maryland began in August 1962. On 18 September 1962, the U.S. military transitioned to a unified designation system for all services, with the aircraft being renamed the P-3 Orion.[4] Paint schemes have changed from early 1960s gloss blue and white, to mid-1960s gloss white and gray, to mid-1990s flat finish low visibility gray with fewer and smaller markings. In the early 2000s, the scheme changed to a gloss gray finish with the original full-size color markings. Large size Bureau Numbers on the vertical stabilizer and squadron designations on the fuselage remained omitted.[6]

P-3 Orions from Japan, Canada, Australia, Republic of Korea and the United States at MCAS Kaneohe Bay during RIMPAC 2010.

In 1963, the U.S. Navy Bureau of Weapons (BuWeps) contracted Univac Defense Systems Division of Sperry-Rand to engineer, build and test a digital computer (then in its infancy) to interface with the many sensors and newly developing display units of the P-3 Orion. Project A-NEW was the engineering system which, after several early trials, produced the engineering prototype, the CP-823/U, Univac 1830, Serial A-1, A-NEW MOD3 Computing System. The CP-823/U was delivered to the Naval Air Development Center (NADC) at Johnsville, Pennsylvania in 1965, and directly led to the production computers later equipped on the P-3C Orion.[7]

Three civilian Electras were lost in fatal accidents between February 1959 and March 1960. Following the third crash the FAA restricted the maximum speed of Electras until the cause could be determined. After an extensive investigation, two of the crashes (in September 1959 and March 1960) were found to be caused by insufficiently strong engine mounts, unable to dampen a whirling motion that could affect the outboard engines. When the oscillation was transmitted to the wings, a severe vertical vibration escalated until the wings were torn from the aircraft.[8][9] The company implemented an expensive modification program, labelled the Lockheed Electra Achievement Program or LEAP, in which the engine mounts and wing structures supporting the mounts were strengthened, and some wing skins replaced with thicker material. All the surviving Electras of the 145 built at that time were modified at Lockheed's expense at the factory, the modifications taking 20 days for each aircraft. The changes were incorporated in subsequent aircraft as they were built.[8]

Sales of airliners were limited as the technical fix did not completely erase the "jinxed" reputation, turboprop-powered aircraft were soon replaced by faster jets.[10] In a military role where fuel efficiency was more valued than speed, the Orion has been in service over 50 years after its 1962 introduction. Although surpassed in production longevity by the Lockheed C-130 Hercules, 734 P-3s were produced through 1990.[2][11] Lockheed Martin opened a new P-3 wing production line in 2008 as part of its Service Life Extension Program (ASLEP) for delivery in 2010. A complete ASLEP replaces the outer wings, center wing lower section and horizontal stabilizers with newly built parts.[12]

In the 1990s, during a U.S. Navy attempt to identify a successor aircraft to the P-3, the improved P-7 was selected over a navalized variant of the twin turbofan-powered Boeing 757, but this program was subsequently cancelled. In a second program to procure a successor, the advanced Lockheed-Martin Orion 21, another P-3 derived aircraft, lost out to the Boeing P-8 Poseidon, a Boeing 737 variant, which entered service in 2013.

The P-3 is equipped with a magnetic anomaly detector (MAD) in the extended tail. This instrument is able to detect the magnetic anomaly of a submarine in the Earth's magnetic field. The limited range of this instrument requires the aircraft to be near the submarine at low altitude. Because of this, it is primarily used for pinpointing the location of a submarine immediately prior to a torpedo or depth bomb attack. Due to the sensitivity of the detector, electromagnetic noise can interfere with it, so the detector is placed in P-3's fiberglass tail stinger (MAD boom), far from other electronics and ferrous metals on the aircraft.[14]

The crew complement varies depending on the role being flown, the variant being operated, and the country that is operating the type. In U.S. Navy service, the normal crew complement was 12 until it was reduced to its current complement of 11 in the early 2000s when the in-flight ordnanceman (ORD) position was eliminated as a cost-savings measure and the ORD duties assumed by the in-flight technician (IFT).[1] Data for U.S. Navy P-3C only.

Once on station, one engine is often shut down (usually the No. 1 engine – the left outer engine) to conserve fuel and extend the time aloft and/or range when at low level. It is the primary candidate for loiter shutdown because it has no generator. Eliminating the exhaust from engine 1 also improves visibility from the aft observer station on the port side of the aircraft.

On occasion, both outboard engines can be shut down, weight, weather, and fuel permitting. Long deep-water, coastal or border patrol missions can last over 10 hours and may include extra crew. The record time aloft for a P-3 is 21.5 hours, undertaken by the Royal New Zealand Air Force's No. 5 Squadron in 1972.

Developed during the Cold War, the P-3's primary mission was to track Soviet Navyballistic missile and fast attack submarines and to eliminate them in the event of full scale war. At its height, the U.S. Navy's P-3 community consisted of twenty-four active duty "Fleet" patrol squadrons home based at air stations in the states of Florida and Hawaii as well as bases which formerly had P-3 operations in Maryland, Maine, and California. There were also thirteen Naval Reserve patrol squadrons identical to their active duty "Fleet" counterparts, said Reserve "Fleet" squadrons being based in Florida, Pennsylvania, Maryland, Michigan, Massachusetts (later relocated to Maine), Illinois, Tennessee, Louisiana, California and Washington. Two Fleet Replacement Squadrons (FRS), also called "RAG" squadrons (from the historic "Replacement Air Group" nomenclature) were located in California and Florida. The since-deactivated squadron in California provided P-3 training for the Pacific Fleet, while the squadron in Florida performed the task for the Atlantic Fleet. These squadrons were also augmented by a test and evaluation squadron in Maryland, two additional test and evaluation units that were part of an air development center in Pennsylvania and a test center in California, an oceanographic development squadron in Maryland, and two active duty "special projects" units in Texas and Hawaii, the latter being slightly smaller than a typical squadron.

Reconnaissance missions in international waters led to occasions where Soviet fighters would "bump" a P-3, either operated by the U.S. Navy or other operators such as the Royal Norwegian Air Force. On 1 April 2001, a midair collision between a United States Navy EP-3E ARIES II signals surveillance aircraft and a People's Liberation Army Navy (PLAN) J-8II jet fighter-interceptor resulted in an international dispute between the U.S. and the People's Republic of China (PRC) called the Hainan Island incident.[15]

The U.S. Navy remains the largest P-3 operator, currently distributed between a single fleet replacement (i.e., "training") patrol squadron in Florida(VP-30), 12 active duty patrol squadrons distributed between bases in Florida, Washington and Hawaii, two Navy Reserve patrol squadrons in Florida and Washington, one active duty special projects patrol squadron (VPU-2) in Hawaii, and two active duty test and evaluation squadrons. One additional active duty fleet reconnaissance squadron (VQ-1) operates the EP-3 Ariessignals intelligence (SIGINT) variant at Naval Air Station Whidbey Island, Washington.

In January 2011, the U.S. Navy revealed that P-3s have been used to hunt down "third generation" narco subs.[16] This is significant because as recently as July 2009, fully submersible submarines have been used in smuggling operations.[17]

In October 1962, P-3A aircraft flew several blockade patrols in the vicinity of Cuba. Having just recently joined the operational Fleet earlier that year, this was the first employment of the P-3 in a real world "near conflict" situation.

Beginning in 1964, forward deployed P-3 aircraft began flying a variety of missions under Operation Market Time from bases in the Philippines and Vietnam. The primary focus of these coastal patrols was to stem the supply of materials to the Viet Cong by sea, although several of these missions also became overland "feet dry" sorties. During one such mission, a small caliber artillery shell passed through a P-3 without rendering it mission incapable. During another overland mission, it is rumored, but not confirmed, that a P-3 shot down a North Vietnamese MiG with Zuni missiles.[18] The only confirmed combat loss of a P-3 also occurred during Operation Market Time. In April 1968, a U.S. Navy P-3B of Patrol Squadron 26 (VP-26) was downed by anti-aircraft artillery (AAA) fire in the Gulf of Thailand with the loss of the entire crew. Two months earlier, in February 1968, another one of VP-26's P-3B aircraft was operating in the same vicinity when it crashed with the loss of the entire crew. Originally attributed to an aircraft mishap at low altitude, later conjecture is that this aircraft may have also fallen victim to AAA fire from the same source as the April incident.[19]

A U.S. Navy F-14 Tomcat escorts an Iranian P-3F Orion over the Indian Ocean - 1981

Lockheed produced the P-3F variant of the P-3 Orion, for Iran. Six examples were delivered to the former-Imperial Iranian Air Force (IIAF) in 1975 and 1976.

Following the Iranian Revolution in 1979, the Orions continued in service, after the IIAF was renamed the Islamic Republic of Iran Air Force (IRIAF). They were used in the Tanker War phase of the Iran-Iraq War and were operated by one of the most successful squadrons of the IRIAF during that conflict. A total of four P-3Fs remain in service.

On 2 August 1990, Iraq invaded Kuwait and was poised to strike Saudi Arabia. Within 48 hours of the initial invasion, U.S. Navy P-3C aircraft were among the first American forces to arrive in the area. One was a modified platform with a prototype system known as "Outlaw Hunter." Undergoing trials in the Pacific after being developed by the Navy’s Space & Naval Warfare Systems Command (SPAWAR), "Outlaw Hunter" was testing a specialized over-the-horizon targeting (OTH-T) system package when it responded. Within hours of the start of the coalition air campaign, "Outlaw Hunter" detected a large number of Iraqi patrol boats and naval vessels attempting to move from Basra and Umm Qasr to Iranian waters. "Outlaw Hunter" vectored in strike elements which attacked the flotilla near Bubiyan Island destroying 11 vessels and damaging scores more. During Desert Shield, a P-3 using infrared imaging detected a ship with Iraqi markings beneath freshly-painted bogus Egyptian markings trying to avoid detection. Several days before the 7 January 1991 commencement of Operation Desert Storm, a P-3C equipped with an APS-137 Inverse Synthetic Aperture Radar (ISAR) conducted coastal surveillance along Iraq and Kuwait to provide pre-strike reconnaissance on enemy military installations. A total of 55 of the 108 Iraqi vessels destroyed during the conflict were targeted by P-3C aircraft.[20]

The P-3 Orion's mission expanded in the late 1990s and early 2000s to include battlespace surveillance both at sea and over land. The long range and long loiter time of the P-3 Orion have proved to be an invaluable asset during Operation Iraqi Freedom and Operation Enduring Freedom. It can instantaneously provide information about the battlespace it can see to ground troops, particularly the U.S. Marines.[1]

Although the P-3 is a Maritime Patrol Aircraft, armament and sensor upgrades in the Anti-surface Warfare Improvement Program (AIP)[21] have made it suitable for sustained combat air support over land.[21] Since the start of the current war in Afghanistan, U.S. Navy P-3 aircraft have been operating from Kandahar in that role.[22] Royal Australian Air Force AP-3C Orions operated out of Minhad Air Base in the UAE from 2003 until their withdrawal in November 2012. During the period 2008–2012, the AP-3C Orions conducted overland intelligence, surveillance and reconnaissance tasks in support of coalition troops throughout Afghanistan.[23]

Three P-3C Orions, delivered to the Pakistan Navy in 1996 and 1997 were operated extensively during the Kargil conflict. After the crash of one, the type was grounded due to the loss of an entire crew; nonetheless, the aircraft were maintained in an armed state and airworthy condition throughout the escalation period of 2001 and 2002. In 2007, they were used by the navy to conduct signals intelligence, airborne and bombing operations in a Swat offensive and Operation Rah-e-Nijat. Precision and strategic bombing missions were carried out by the Orions, and in 2007, intelligence management operations were conducted against Taliban and al-Qaeda operatives.[25]

On 22 May 2011, two out of the four Pakistani P-3Cs were destroyed in an attack on PNS Mehran, a Pakistani Naval station in Karachi.[26] The Pakistani fleet had been readily used in overland, counter-insurgency operations. In June 2011, the U.S. agreed to replace the destroyed aircraft with two new ones, with delivery to follow later.[27] In February 2012, the U.S. delivered two, additional P-3C Orion aircraft to the Pakistan Navy.[28]

The Spanish Air Force deployed P-3s to assist the international effort against piracy in Somalia. On 29 October 2008, a Spanish P-3 aircraft patrolling the coast of Somalia reacted to a distress call from an oil tanker in the Gulf of Aden. To deter the pirates, the aircraft flew over the pirates three times as they attempted to board the tanker, dropping a smoke bomb on each pass. After the third pass, the attacking pirate boats broke off their attack.[29] Later, on 29 March 2009, the same P-3 pursued the assailants of the German navy tanker Spessart (A1442), resulting in the capture of the pirates.[30] In April 2011, the Portuguese Air Force also contributed to Operation Ocean Shield by sending a P-3C[31] which had early success when on its fifth mission detected a pirate whaler with two attack skiffs.[32]

Several U.S. Navy P-3C Orions, and two Canadian CP-140 Auroras, a variant of the Orion, have participated in maritime surveillance missions over Libyan waters in the framework of enforcement of the 2011 no-fly zone over Libya.[33][34]

A U.S. Navy P-3C Orion supporting Operation Odyssey Dawn engaged the Libyan coast guard vessel Vittoria on 28 March 2011 after the vessel and two smaller craft fired on merchant ships in the port of Misrata, Libya. The Orion fired AGM-65 Maverick missiles on Vittoria, which was subsequently beached.[35]

AP-3C: Royal Australian Air Force P-3C/W aircraft which have been extensively upgraded by L-3 Communications with new mission systems, including an Elta SAR/ISAR radar and a GD-Canada acoustic processor system.

CP-140A Arcturus: Three P-3s without ASW equipment for Canadian Aurora crew training and various coastal patrol missions.

P-7 proposed new-build and improved variant as a P-3 Orion replacement later canceled.

Orion 21 proposed new-build and improved variant as a P-3 Orion replacement; lost to the Boeing P-8 Poseidon.

P-3K: Royal New Zealand Air Force P-3K2 aircraft which have been fully upgraded with totally new mission systems by L-3 Mission Integration Division, Greenville, Texas. The flight deck now has ‘glass’ instrumentation and navigation computer automation. The Tactical Rail (Tacrail) has been completely refitted with modern sensors, communication and data management systems.

In 2002, the RAAF received significantly upgraded AP-3C. Also known as Australian Orions they are fitted with a variety of sensors. They include digital multi-mode radar, electronic support measures, electro-optics detectors (infra-red and visual), magnetic anomaly detectors, identification friend or foe systems, and acoustic detectors.[37]

Chilean Navy – four P-3A; based at Base Aeronaval Torquemada, Concón. Three used as patrol aircraft, one used for personnel transport. Chile plans to extend their service lives past 2030 by changing the wings, modernizing the engines, and integrating the AGM-84 Harpoon anti-ship missile.[39]

Royal New Zealand Air Force – six P-3K2 (5 Sqn); based in RNZAF Base Auckland. Operated by 5 SQN. Five were originally delivered in 1966 as P-3Bs. Another was purchased from the RAAF in 1985, following which all were upgraded to their current standard. Currently undergoing various mission system upgrades by L-3 Communications Canada and now designated as P-3K2. Due to be replaced in 2050 with equivalent level of capability, either manned or unmanned.

Pakistan Naval Air Arm – ~Four P-3C; based in Naval aviation base Faisal, Karachi. Upgraded P-3C MPA and P-3B AEW models (equipped with Hawkeye 2000 AEW system) ordered in 2006,[43] first upgraded P-3C delivered in early 2007. In June 2010, two more upgraded P-3Cs joined the Pakistan Navy with anti-ship and submarine warfare capabilities.[44] Two aircraft were destroyed in an attack by armed militants at the Mehran Naval Airbase.

Spanish Air Force – Two P-3A HWs, four P-3B being upgraded to P-3M, based at Morón Air Base. The Spanish AF bought five P-3B from Norway in 1989 and it was planned to upgrade all five to M standard, however, due to budgetary constraints only four are to be upgraded, the remaining aircraft being used as spares source.

Republic of China Air Force(1966–1967) – Least known of all P-3 family. Three P-3As (149669, 149673, 149678) were obtained by CIA from the U.S. Navy under Project STSPIN in May 1963, as the replacement aircraft for CIA's own covert operation fleet of RB-69A/P2V-7U versions. Converted by Aerosystems Division of LTV at Greenville, Texas, the three P-3As were simply known as "black" P-3As under "Project Axial". Officially transferred from U.S. Navy to CIA on June/July 1964, LTV Aerosystems converted the three aircraft to be both ELINT and COMINT platform. First of three "black" P-3As arrived in Taiwan and officially transferred to ROCAF's top secret Black Bat Squadron on 22 June 1966. Armed with four Sidewinder short range AAM missiles for self-defense, the three "black" P-3A flew peripheral missions along the China coast to collect SIGINT and air samples. When the project was terminated in January 1967, all three "black" P-3As were flown to NAS Alameda, CA, for long term storage. In September 1967, Lockheed at Burbank, converted two of the three aircraft (149669 and 149678) into the only two EP-3B examples in existence in the world, while the third aircraft (149673) was converted by Lockheed in 1969–1970 to serve as a development aircraft for various electronic programs. The two EP-3Bs known as "Bat Rack", owing to their short period of service with Taiwan's "Black Bat" Squadron, were issued to U.S. Navy's VQ-1 Squadron in 1969 and deployed to Da Nang, Vietnam. Later, the two EP-3Bs were converted to EP-3E ARIES, along with seven EP-3As. The two EP-3Es retired in the 1980s, when replaced by 12 EP-3E ARIES II versions.[46]

Republic of China Navy – 12 P-3Cs (Ordered, with deliveries starting in 2012), with three "spare" airframes that might be converting to EP-3E standard; based in south part of the island and offshore island.[47] In May 2014 Lockheed Martin were awarded a contract to upgrade and overhaul all 12 P-3Cs for completion by August 2015.[48]

United States Navy – 154 P-3Cs and EP-3Es; additional P-3A, P-3B, P-3C and EP-3J aircraft in long-term storage at AMARC[50] The U.S. Navy plans to reduce this number to 130 by 2010.[1] The government of Singapore has expressed an interest in buying surplus P-3C aircraft from the U.S. Navy.[51]

30 January 1963: United States Navy P-3A 149762 was lost at sea in the Atlantic Ocean, 14 crew killed.[56]

6 March 1969: USN P-3A 152765 coded RP-07 of VP-31 crashed at NAS Lemoore, California, at the end of a practice ground control approach (GCA) landing, all six crew died.

28 January 1971: Commander Donald H. Lilienthal, USN flew a P-3C Orion to a world speed record for heavyweight turboprops. Over 15–25 kilometers, he reached 501 miles per hour to break the Soviet Il-18's May 1968 record of 452 miles per hour.

26 May 1972: USN P-3A 152155 disappeared over the Pacific Ocean on a routine training mission after departing NAS Moffett Field, California with the loss of eight crew members.[57]

3 June 1972: While attempting to fly through the Straits of Gibraltar, en route from Naval Station Rota, Spain to Naval Air Station Sigonella, Sicily, a U.S. Navy P-3A of Patrol Squadron 44 (VP-44) hit a mountain in Morocco, resulting in the death of all 14 people on board the aircraft.[58]

12 April 1973: A United States Navy P-3C 157332 operating from NAS Moffett Field in Sunnyvale, California collided with a Convair CV-990 (N711NA) operated by NASA during approach to runway 32R. The aircraft crashed on the Sunnyvale Municipal Golf Course, half a mile short of the runway, resulting in destruction of both aircraft and the death of all but one.[59]

11 December 1977: USN P-3B 153428 from Patrol Squadron 11 operating from Lajes Field in the Azores crashed on mountainous El Hierro (southwesternmost of the Canary Islands) in poor visibility. There were no survivors from the crew of 13.[60]

26 April 1978: USN P-3B 152724 from Patrol Squadron 23 (VP-23) crashed on landing approach to Lajes Field in the Azores. Seven of the crew were killed and the plane sank into deep water preventing recovery to assess the cause of the crash.[61]

22 September 1978: USN P-3B 152757 from Naval Air Station Brunswick Patrol Squadron 8 (VP-8) disintegrated over Poland, Maine on 22 September 1978. An over-pressurized fuel tank caused the port wing to separate at the outboard engine.[62] The detached wing sheared off part of the tail; and aerodynamic forces caused the remaining engines and starboard wing to detach from the fuselage. Debris rained down near the south end of Tripp Pond shortly after 12:00. There were no survivors from the plane's 8-man crew.[63]

26 October 1978: USN P-3C 159892 coded AF-586 from NAS Adak Patrol Squadron 9 (VP-9) ditched at sea after an engine fire caused by a propeller malfunction. Ten of the 15-man crew were rescued by a Soviet trawler.[64]

27 June 1979: P-3B 154596 from NAS Cubi Point, Philippines Patrol Squadron 22 (VP-22) had a propeller overspeed shortly after departure. The number 4 propeller then departed the aircraft striking the number three with a subsequent fire on that engine. While attempting an overweight landing with 2 engines out, the aircraft stalled, rolled inverted and crashed in Subic Bay just past Grande Island. Four crew and one passenger were killed in the crash.[65]

16 June 1983: USN P-3B 152720 coded YB-06 from Barber's Point, Oahu, Hawai'i [NAS Barbers Point] Patrol Squadron 1 (VP-1), crashed into a mountain top in fog and low clouds, on the Napali Coast between the Hanapu and Kalalau valleys in Kauai, Hawai'i shortly after 0400 hours, killing all 14 on board.[65][66]

13 September 1987: A Royal Norwegian Air Force P-3B "602" is hit from below by a Russian AF Sukhoi Su-27 of the 941st IAP V-PVO. The Su-27 flew below the P-3's starboard side, then accelerated and pulled up, clipping the #4 engine's propellers. The Propeller shrapnel hit the Orion's fuselage and caused a decompression. There were no injuries and both aircraft returned safely to base.[67]

21 March 1991: While on a training mission west of San Diego, California, two U.S. Navy Orions assigned to Patrol Squadron 50 (VP-50) at NAS Moffett Field collided in midair, killing all 27 people on board both aircraft.[68]

26 April 1991: AP-3C A9-754 of the RAAF lost a wing leading edge and crashed into shallow water in the Cocos Island, one crewman was killed. Aircraft was cut up and used as an artificial reef.[69] The head investigator of this incident was RAAF FLTLT Richard Hall[70]

25 March 1995: USN P-3C 158217 assigned to Patrol Squadron Forty-Seven (VP-47) was returning from a training mission in the North Arabian Sea when it suffered catastrophic engine failure of the no. 4 engine. The aircraft ditched at sea six miles from Masirah Island, Oman. All 11 crew members were rescued by the Royal Omani Air Force.[71]

16 October 1991: P-3A N924AU of Aero Union crashed into a mountain in Montana, United States killing both crew.[73]

22 May 2011: Twenty Tehrik-i-Taliban Pakistan militants claiming to avenge Osama Bin Laden's death destroyed two Pakistan Navy P-3C Orions during an armed attack at PNS Mehran, a heavily guarded base of the Pakistan Navy located in Karachi.[74] The aircraft had been readily used by the Pakistani military in overland counter-insurgency surveillance operations.[75]

Hardpoints: 10 wing stations in total (3x on each wing and 2x on each wing root) and eight internal bomb bay stations with a capacity of 20,000 lb (9,100 kg)[1] and provisions to carry combinations of: